Apparatus for electrotreating metal slide fasteners



Aug. 8, 1950 w. MIKULAS APPARATUS FOR EIECTROTREATING IEIAL SLIDE FASTENERS Filed Jan. 5, 1945 3 Sheets-Sheet 1 INVENTOR. Wdli a1" mun-Mus W a! %44 AGENT w. MlKULAS 2,517,907

APPARATUS FOR awc'mo'mmnuc METAL suns FASTENERS Aug. 8, 1950 3 Sheets-Sheet 2 Filed Jan. 5, 1945 INVENT OR.

lfllllam. lfliKulas AGENT W w 0 m r 7 a J m MN 1 m E 5 w v. 6 I m M; u 2 K m M w s l w 3 /H a ffi m m x uvv A MG M \H .I W. U P41 mm J 8 W f J 9 2 Aug. 8, 1950 Filed Jan 5, 1945 Patented Aug. 8, 1950 APPARATUS FOR ELECTROTREATING METAL SLIDE FASTENERS Wiliiam Mikulas, West Brighton, N. Y., assignor to Conmar Products Corporation, Newark, N. J., a corporation of New Jersey Application January 5, 1945, Serial No. 571,705

13 Claims. 1

My invention relates to a method of. and to equipment for, electrotreating metal slide fastener elements. More particularly, the invention pertains to electrotreating slide fastener elements when spacedly attached along an edge of a tape for cooperation with mating slide fastener elements, such tape when provided with a series of slide fastener elements being generally referred to as a slide fastener stringer.

Great difliculties are encountered in electrotreating scoops or slide fastener elements when mounted on a carrier of an electrically non-conducting material, such as a cotton tape. The primary object of this invention is to generally improve the method of, and the means for, electrolytically plating or otherwise electrolytically coating of scoops or slide fastener elements mounted on a non-conducting tape.

In surface treating scoops by electrolytic means,

it has been the practice to treat loose or unattached scoops and to secure already treated scoops to tapes. Such treatment is only applicable to a method of manufacturing slide fasteners wherein scoops prior to their attachment are individually finished and may individually be subjected to various treatments. However, since methods of manufacturing slide fasteners in this way are relatively slow and are being more and more abandoned, the electrolytic treatment of unattached scoops is also being relinquished. It is also customary to weave into, or otherwise intimately unite with, a slide fastener tape a metal conductor to provide electrical contact along all of the scoops attached to that tape. But the incorporation of metal conductors in a tape usually impairs the flexibility of the stringer and thus involves a disadvantage. It has also been suggested to electroplate scoops or slide fastener elements by means of special equipment. In one of the suggested apparatus a. slide fastener stringer is passed around metallic rollers arranged for individual rotation about their axis. This apparatus is complicated. It is an object of this invention to provide a simple and economic means for electrically charging the scoops of at least one slide fastener stringer at a time while it passes through the electrolytic bath.

Recently a suggestion has been made to use an external conductor in strip form for providing electrical contact between the engaged scoops of a slide fastener. Yet this suggestion involves the disadvantage that the conductor suggested will readily be crushed and ruined and cannot be used in continuous processes. One of the main objects of my invention centers about the provision of an external conductor which will be 2 temporarily interlocked with at least one stringer but which, from a. practical point of view, is not perishable and can be used in continuous processes without the need, incident to the aforesaid prior suggestion, of restoring the used and ruined strip to a new use or of discarding the strip.

Another object of my invention is to provide conductors adapted to individually engage each slide fastener element of a series of such elements when attached in uniformly spaced relation to a tape of non-conducting material. The conductor according to my present invention is flexible and capable of being fixed when united with a slide fastener stringer, and it is used in endless form.

A further object of my invention is to provide an apparatus which connects at least one stringer, before it enters the electrolytic bath, with a suitable conductor and which disconnects both after leaving this bath.

Still another object is to provide means for regenerating those parts of the equipment necessarily plated during the passage through an electroplating bath.

To the accomplishment of the foregoing and other more particular objects which will hereinafter appear, my invention consists in the method steps and apparatus elements and their relation one to the other, as hereinafter are more particularly described in the specification and sought to be defined in the claims. The specification is accompanied by drawings, in which:

Fig. 1 is a fragmentary, partially sectioned plan view illustrating the operation of one form of the pull-up fixture according to the invention, the pull-up fixture being used to lock two slide fastener stringers into a coil spring or to unlock such assembly;

Fig. 2 is an end elevation of the view of Fig. 1.

Fig. 3 is an enlarged fragmentary view toward the beaded edge of one of the two stringers shown in Fig. 1, and illustrating the engagement of the coil spring with the scoops of that stringer;

Fig. 4 is a diagrammatic plan view illustrating one form of a plating apparatus;

Fig. 5 is a side elevation of the same with parts removed;

Fig. 6 is explanatory of the operation of the apparatus of Figs. 4 and 5;

Fig. '7 is a fragmentary, isometric view showing diagrammatically an electrotreating apparatus;

Fig. 8 is explanatory of the operation of the apparatus of Fig. '7;

Fig. 9 is a cross section through the conductor used in the apparatus of Fig. '7;

Fig. is a, fragmentary, partially sectioned view illustrating, in plan, the pulling up of a stringer with the conductor of Fig. 9 by means. of another form of a pull-up fixture.

Referring to the drawing, the apparatus in all forms shown is intended to electrolytically treat work having metallic eleznents attached in spaced relation upon the edge of a continuous non-conducting carrier. The specific example shown is a slide fastener stringer comprising, in

1, the two non-conducting textile tapes 26 and metallic fastener elements 28, or in Figs. 7 and 10, the single non-conducting textile tape 12 with metal fastener elements 28 indicated along its edge. In accordance with the present invention. the apparatus comprises not only a tank containing an electrolyte, but also an endless supporting fiexible conductor comprising conductor metallic elements formed, dimensioned and spaced for temporary interlocking enga ment with each of the work metallic elements. and also a fixture for guiding the conductor and the work into engagement in such fashion that the conductor elements are interlocked with the work elements. In Fig. 1 a fragment of the endless supporting conductor is shown at it, and

the fixture at (8, while in Fig, 10 the endless supportingconductor is shown at 12, and the fixture at M.

.As is usual in electroplating, the tank is provided with an electrode immersed in the electrolyte,-a.nd the polarity of the potential applied to the electrode .depends on the particular metal being treated. In other words, the treatment may be either cathodic or anodic.

If desired, the endless supporting conductor may be de-plated, and for this purpose a deplating tank 544s shown in Fig. 4.. However, the advisability of tie-plating depends on the economics of the process, considering for example, the value of the metal recovered, and the cost of the endless conductor which, if not de-plated, must eventually be discarded and replaced. That de-plating is optional is shown in Figs. 6 and 8, Fig. 6 schematically showing the process with de-plating, and Fig. 8 schematically showing the process without de-plating.

The endless supporting conductor is illustrated in two forms. In Figs. 1, 2 and 3 the endless supporting conductor is a helical coiled spring it which is meshed by the fixture [8 with two continuous slide fastener stringers 25. In Figs. 9 and 10 the endless supportin conductor is a slide fastener stringer having not only a tape 82 and fastener elements 84, but also an electrical conductor 88 extending longitudinally thereof in contact with and connecting the metallic elements. As here illustrated, the conductor forms a part of the head of the fastener tape. Fig. 10 shows how-a fixture It, generally resembling a slider, serves to guide the endless supporting conductor l2 and the unplated slide fastener (2 into meshing engagement.

Considering the invention in greater detail. andreferringfirsttoFigslandzofthedrawing, a. pull-up fixture Ill serves to connect two identical slide fastener stringers It with a. coil spring It of the helical type. Thefixture (0 con-. sists of a mainbodv 4G and a tube 18. The body comprises an annular portion and two pairs of parallel walls 22, each wall havin inturned side flanges 24. The tube It is, as shown inFig.1,atthewideendoftheb0dy forms acontinuation of the annular portion 25. The body 16 defines a channel Ch, shown in Fig.

1, functioning to lock the stringers into the coil spring or to separate the stringers from the coil spring when engaged with each other. The coupling and uncoupling action of the pull-up fixture it conforms, as will hereinafter be shown, to the respective direction in which the coil spring and stringers are fed into the pull-up fixture. 'Each of the stringers 12 comprises a tepe having slide fastener elements 28 at- Zach-:0. to its beaded edge 39. The tapes and beads being of a non-conducting material, there can be no electrical contact between the fastener elements of either stringer. The coil spring It is to furnish a continuous contact along the fastener elements of each stringer.

From inspection of Figs. 1 and 3, the function of the fixture it will be clear. The stringers i2 and the coil spring Isl are threaded through the fixture in the direction of the arrow X indieated inFig. 1.tha.tis to say, the coil spring is inserted at the free end of the tube is and passed straight through the tube and the annular por-- tion 36 of the fixture body (6, while the stringers are ccnvergently passed through the fixture body. The engagement of the coil spring with the stinger-S takes place in the straight stem of the channel Ch. In order'that the spring be suitable for this engagement. its pitch must be substantially equa to the pitch of the fastener elements, and the diameter of the spring wire substantially equal to the spacing between the fasiener elements. The pitch of the fastener elements is the distance from any point on a fastcner element to the corresponding point on the adiacent element of the same stringer, or the of an element plus the spacing between two adjacent elements. Any coil or turn of the coil spring (4, as shown in Fig. 3, touches one fastener element at L and the adjacent fastener element of the same stringer at II. From Fig. 8, it will also be clear that each fastener element of either stringer is .in contact with two adjacentcoils of the spring, for instance, the element 28E with the coils or turns NC and MC (see also Fig. 1). By choosing the correct wire diameter a positive electrical contact between the spring and each of the elements of the two strh ers is secured. In Fig. 1, it is shown how portions of the coil spring, after the engagement of the spring with the stringers, are nested in their seats 5, each seat being formed by two adjacent fastener elements of the same stringer and the respective-tape bead. It will he obvious that a tight fit is necessary to provide a reliable electrical contact.

It will be understood that a pull-up fixture of the type of the fixture 10 can be so constructed as to connect a coil spring with one stringer only.

The apparatus shown in Figs. 4 and 5 illus-- trates the use of the coil spring (4 for electrically charging elements 28 of two slide fastener stringers l2 during the passage through an electroplating bath. A pair of rolls 3|, 3| at the entry side of a. tank 32 pulls the coil spring and the stringers through a pull-up fixture it, which is identical with the fixture l0, shown in Figs. 1 to2,andfunctions heretoconnectthestringers with the coil spring. The coilspring passes in the direction of the arrow Y over a wheel 34, carried on a stand 35. and through the guide tube l8 of the fixture l0. whereas the two stringers ii are convergcntly fed into the pull-up fixture after being prepared for the now following electropic-ting step. The connected structure St.

it leaves the rolls 3|, 3|, is pulled-through the tank 32 by another pair of rolls 38, 38 at the exit side of the tank. The rolls 38, 38' are arranged in the same way as are the rolls 3|, 3|. The rolls 3| and 38 are power driven, whereas the rolls 3|,38' are idle. The driven rolls 3| and 38 are mounted on shafts 40 and 42, respectively, and these shafts are provided with pulleys 44 and 46, respectively, connected to motors (not shown). The idle rolls 3| and 38' are firmly pressed against the stringer tapes. The rolls 3| and 3|, as-well as the rolls and 58, are provided with grooves G disposed circumferentially around the periphery of each roll and adapted to accommodate the coil spring l4. The rolls 48'and 50 are suitably journaled underneath the level 5| of the electroplating bath,

vand the structure St passes under them for the moves toward, and passes around, the guide wheel 34' carried on a stand 36', enters a tank 54,-thereby passing over the entry roll 56,'under the -rolls 58,58 and over the exit roll 56', and

finally returns'to the wheel 34. The rolls 58, 58 guide the coil spring'through the electrolyte in the tank 54." The rolls'56, 58, 58, 56' are likewise-provided with grooves G. 1

. In this electroplating process the tank 32 serves plating purposes whereby not only the slide fastener elements 28 of the two stringers 12 but also the'coil spring H are being plated. The tank 54 is used to discharge into its electrolyte the metal which has been deposited upon the coil spring during its passage through the plating bath of the tank 32.

The positive wire 68 of the plating circuit is connected to the anodes 62 of the plating metal which anodes are suspended in the bath of the tank 32 from insulated bars 64 by hooks 66. Cathodes 68 in the deplating tank 54 are electrically charged by being connected by means of the wire 6| to the negative pole of the source of power used. In operation, the current passes from the anodes through the electrolyte to the structure St because this structure faces the anodes, and hence, has a negative polarity. The current carries metal from the anodes and deposits it on the slide fastener elements and on the coil spring. As soon as the coil spring faces the cathodes 68 in the deplating tank it assumes positive polarity, and the metal deposited on the coil-spring is being stripped.

With the arrangement shown, insulated rolls are used. All of the rolls are formed or covered with a suitable insulating material.

The principle of the electroplating apparatus as shown in Figs. 4 and 5 will be best understood from Fig. 6 in which a slide fastener stringer l2 moving in the direction of the arrow Z'is connected with the coil spring l4 or any other suitable endless electrical conductor moving in the direction of the arrow Q. It will be understood that two slide fastener stringers can just as well be connected with the coil spring. The assem-" bled stringer and conductor passes through the plating tank 32, the conductor supporting the stringer during its passage through the tank. After leaving. this tank the assembled structure is separated whereupon the stringer I2 is subjected to the treatment next following in the manufacturing line while the coil spring I4 passes through the deplating tank 54. The current is supplied from a suitable source I0 to the anodes 62 disposed in the tank 32, and conducted away from the cathodes 68 disposed in the tank 54. While the conductor or coil spring |4 moves through the plating tank, the plating metal is deposited both on the conductor and stringer due to the negative polarity assumed by the conductor. As the conductor moves on into the deplating tank where it faces the cathodes, the metal which has been deposited thereon will be stripped.

The process according to the invention is applicable to any known electrolytic surface treatment, such as, anodizing, providing with a corrosion resistant fihn, electro-color plating, etc.-

In a method of anodizing or anodically oxidizing, for instance aluminum scoops, no second electrolytic bath is needed. The circuit in such anodic oxidation of aluminum includes the anode, formed by the scoops of at least one stringer and bythe conductor connecting the scoops, the electrolyte, and a suitable cathode. Neither is a second tank needed in the method of imparting a corrosion resistant film to metals, an example of which method is disclosed in the co-pending application of Hans Bermann and Sigmund Katz, Ser. No. 564,545, filed November 21, 1944, now abandoned. This electrolytic treatment also uses the connected conductor-stringer-structure as an electrode. I

The modification shown in Fig. 7 difiers in two main respects from that shown in Figs. 4 and 5. In Fig. 7, an apparatus for electrotreating having one tank only is shown. A conductor 12 moving in the direction of the arrow V is connected with a stringer l2 by means of a pull-up fixture I4, and the connected conductor and stringer is guided through the electrolytic bath in the tank 16 (shown in phantom) and thence through the pull-up fixture 74 to separate the assembly. The conductor supports the stringer in its passage through the tank 16. One wire of the electrotreating circuit is connected to the conductor by means of a spring and ring contact 18, and the other wire is connected to an electrode in the tank 16. The principle of the apparatus of Fig. 7 is most clearly illustrated in Fig. 8.

The conductor used in the apparatus of Fig. 7 is more clearly shown in Fig. 9. It is generally designated as 12, and it resembles a slide fastener stringer in that it comprises a tape 82 having metal members 84 spacedly clamped around a beaded edge 86. The bead 86 is formed by two cords 88 and 98 disposed on opposite sides of the tape. While the tape 82 and cord 88 are of a non-conducting material, the cord 98 consists of a braided metallic cord and is conducting. Referring now to Fig. 10, the pull-up fixture 14 of Fig. '7 functions like a slider for slide fasteners to couple the conductor 12 and the slide fastener stringer |2 together or to uncouple same. The members 84 are secured to the tape 82 .in the same spaced relation as are the slide fastener elements 28 to the tape 26, and are provided with interlocking means (projections P and depressions D) adapted to cooperate with the interlocking means of the fastener elements 28. The members 84 fit tightly between the fastener elements 28 and secure a substantial electrical contact between the conducting cord 98 and each fastener element. I 1

mom-soar Ina as continuous: electrotreating process great lengths of:=sl-ide "fastener stringers must be sub-' jectedrt'o the electrolytic bath. It isto be under-- stood that the novel features incorporated in the apparatus shown in Figs. 4 and 5 and Fig. 7, respectively,

be subjected tothe electrotreatment at any one instant; This -'may be'donein any known way,

for-instance; by passing the stringers in zigzagturns; throughthe electrolytic baths. With such an arrangement it will be-necessary to provideadditional positive driving. means distributed.

vantages in-the and operation-thereof will,-;

Irbelievegbe apparent from-the above detailedrdescription thereof. It.will be further apparent that-many changes maybe made both in the -appar atus and methodywithout departing from the spirit ofthe' invention 'defineduin 'the" Iclaim: A 1..:Apnaratusfi'or'electrolytically treating work having, metallic; elements attached: in spaced --relation-- upon the edge of a continuous electrically non-conducting carrier; said apparatuscomprisinga tank-containing-an-electrolyte, an endless;- supporting; flexible electrical-conductor comprising a helical coiled'sprin'g;-the turns-of the spring-- being dimensioned and-.spac'edrfor temporary interlocking engagement" with" each. of the' work metallic elements, a, fixture for guiding the conductcr and the work into engagement in such fashion as to temporarily interlock the spring turns' into engagement with the successive work" metallic-elements, means fcr feeding the spring engaged and supported work through the tank, and-afix-ture for separating the spring from the work.

2. Apparatus for electrolytically treating the spaced, electrically unconnected, metallic fastener elements of a continuous slide fastener stringer comprising a tank containing an electrolyte, an endless, supporting, flexible electrical conductor comprising spaced, electrical-conductor-connected metallic elements, the spaced metallic elements having substantially the same pitch as the fastener elements and being of a contour to permit temporary interlocking engagement' with each of the fastener elements, means for temporarily interlocking the conductor connected metallic elements into engagement witheach of the fastener elements, means for feeding the endless, flexible conductor-engaged and" supported stringer through the tank, and means. for separating the endless, supporting conductor from the stringer.

3. Apparatus for electrolytically treating the spaced, electrically unconnected, metallic fastener elements of a continuous slide fastener stringer comprising a tank containing an electrolyte, an endless, supporting, flexible, electrical conductor comprising a helical coiled.spring,.the.

are: applicable 'toan apparatus. wherein any desired-length of a stringer will turns of-tthespring having'substantially the same pitch-'as'the fastenerelements, means for temporarilyinterlocking the spring turns into engagement withi'each of the fastener elements, means for :feeding'the-spring-engaged and supportedstringer' through the tank, and'means for separatingthe springfrom the stringer.

4; Apparatus for electrolytically treating the spaced, electrically unconnected, metallic fas- 10.tener-elements '-of' a continuous slide fastener stringer-comprising a tank containing an electrolyte,= .an-'endless-,- supporting, flexible, electrical conductor comprising a slide fastener. stringer provided with: an electrical conductor extending lcngitudinallythereof in contact with and connecting itsvmetalli'c' elements, said conductor connected metallic elementshavin substantially thesame; pitch asthe-fastener elements on said continuous-- stringer, means for temporarily interlocking into, engagement the electrically connected" metallic elements with eachof the electr-ically unconnected; fastener elements, means for feeding the temporarilyinterlocked stringers throughthe-tank; and means for separating them. Y

-5.- Apparatus-for electrolytically treating the spaced, electricallyunconnected metallic fastener elements ofa continuous slide fastener stringer,

comprising a-tank containing an electro yte, an

anode in contact with the electrolyte, an endless,

"supporting, flexiblegelectrical" conductor com.-

prising'spaced, electrical conductor connected metallic elements, theispaced metallic elements-- respect to the potential of the anode, means for temporarily interlockingthe conductor connected metallic elements into engagement with each of the fastener elements to thereby form the cathode,;means for feeding the endless, fiexibleconductor-engaged and supported stringer through the tank, and-means for separating the endless, flexible' conductor from the stringer.

6. Apparatus for electrolytically treating the spaced, electrically unconnected, metallic fastener elements of a continuous slide fastener stringer, ,comprising'a tank containing an electrolyte, an anode in contact with the electrolyte, an endless, supporting, flexible, electrical'conductor comprising a helical coiled spring, the turns of the spring havingsubstantially the same pitch as the fastener elements, the-spring having a negative potential with respect to the potential of the anode, meansfor temporarily interlocking the spring turns-into engagement with each of the fastener elements to thereby form the cathode, means for 1 feeding thespring engaged and supported stringer through.- the tank, and means for separating the spring from'the stringer;

'7. Apparatus forelectrolytically treating the spaced, electrically -unconnected, metallic fas- 75. theendiessifleizibleconductorhaving-a negative ant-"tor potential with respect to the potential of the anode, means for temporarily interlocking into engagement the electrically connected metallic elements with each of the electrically unconnected fastener elements to thereby form the cathode, means for feeding the temporarily interlocked stringers through the tank, and means for separating them.

8. Apparatus for anodizing the spaced, electrically unconnected aluminum fastener elements of a continuous slide fastener stringer, comprising a tank containing an electrolyte, a cathode in contact with the electrolyte, an endless, supporting, flexible, electrical conductor comprising spaced, electrical conductor connected metallic elements, the spaced metallic elements having substantially the same pitch as th fastener elements and being of a contour to permit temporary interlocking engagement with each of the metallic fastener elements, the endless, flexible conductor having a positive potential with respect to the potential of the cathode, means for temporarily interlocking the conductor connected metallic elements into engagement with each of the fastener elements to thereby form the anode, means for feeding the endless, conductor-engaged and supported stringer through the tank, and means for separating the endless, flexible conductor from the stringer.

9. Apparatus for aIlOdiZing the spaced, electrically unconnected, aluminum fastener elements of a continuous slide fastener stringer, comprising a tank containing an electrolyte, a cathode in contact with the electrolyte, an endless, supporting, flexible, electrical conductor comprising a helical coiled spring, the turns of the spring having substantially the same pitch as the stringer fastener elements, the spring having a positive potential with respect to the potential of the cathode, means for temporaril interlocking the spring turns into engagement with each of the fasener elements to thereb form the anode, means for feeding the spring-engaged and supported stringer through the tank, and means for separating the spring from the stringer.

10. Apparatus for anodizing the spaced, electrically unconnected, aluminum fastener elements of a continuous slide fastener stringer comprising a tank containing an electrolyte, a cathode in contact with the electrolyte, an endless, supporting, flexible, electrical conductor comprising a slide fastener stringer provided with an electrical conductor extending longitudinally thereof in contact with and connecting the metallic elements, said conductor connected metallic elements having substantially the same pitch as the fastener elements on said continuous stringer, the endless, flexible conductor having a positive potential with respect to the potential of the cathode, means for temporarily interlocking into engagement the electrically connected metallic elements with each of the electrically unconnected fastener elements to thereby form the anode, means for feeding the temporarily interlocked stringers through the tank, and means for separating them,

11. Apparatus for electroplating the spaced, electrically unconnected, metallic fastener elements of a continuous slide fastener stringer, comprising a tank containing an electrolyte, an anode in contact with the electrolyte, an endless, supporting, flexible, electrical conductor comprising spaced, electrical conductor connected metallic elements, the spaced metallic elements having substantially the same pitch as the fastener ele-.

i0 ments and being of a contour to permit temporary interlocking engagement with each of the metallic fastener elements, means for progressively and temporarily interlocking the conductor connected metallic elements into engagement with each of the electrically unconnected fastener elements, means for separating the endless supporting con,-

ductor from the stringer as they leave the tank, a

second tank containing an electrolyte, a cathode in contact with the electrolyte of said second tank,

and means for feeding the endless, flexible conductor through both tanks and the aforementioned means.

12. Apparatus for electroplating the spaced, electrically unconnected metallic fastener elements of a continuous slide fastener stringer comprising a tank containing an electrolyte, an anode in contact with the electrolyte, an endless, supportingflexible, electrical conductor comprising a helical coiled spring, the turns of the spring having substantially the same pitch as the stringer fastener elements, means for progressively and temporarily interlocking the spring turns into engagement with each of the fastener elements, means for separating the spring from the stringer as they leave the tank, a second tank containing an electrolyte, a cathode in contact with the electrolyte of said second tank, and means for feeding the spring through both tanks and the aforementioned means.

13. Apparatus for electroplating the spaced, electrically unconnected, metallic fastener elements of a pair of continuous slide fastener stringers, the pitch of the fastener elements on both stringers being substantially the same,- comprising a tank containing an electrolyte, an anode in contact with the electrolyte, an endless, supporting, flexible, electrical conductor comprising a helical coiled spring, the turns of the spring having substantially the same pitch as the fastener elements on the pair of stringers to permit temporary interlocking engagement with each of the metallic fastener elements, means for progressively and temporarily interlocking the spring turns into engagement with each of the electrically unconnected fastener elements of both stringers, means for separating the spring from the stringers as the stringers and spring leave the tank, a second tank containing an electrolyte, a cathode in contact with the electrolyte of said second tank, and means for feeding the spring through both tanks and the aforementioned means.

WILLIAM MIKULAS.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 653,715 Van Gestel July 1'7, 1900 924,324 Dalton June 8, 1909 2,011,328 Tuttle Aug. 13, 1935 2,047,418 Kronshein July 14, 1936 2,052,962 Booe Sept. 1, 1936 2,293,810 Domm Aug. 25, 1942 2,334,054 Wooters Nov. 9, 1943 2,342,811 Martin Feb. 29, 1944 2,344,548 Goetz Mar. 21, 1944 2,399,964 Ward May 7, 1946 FOREIGN PATENTS Number Country Date 9,289 Great Britain in June 24:, 1936 

